In general, the components which can be automatically inserted into the printed circuit board (PCB) are classified into three types, including jumper wires, axial lead parts and radial lead parts. During automatic insertion of components, it is necessary to adopt different inserting techniques for different components, for instance, JVK machines are used to insert jumper wires, AVK machines are used to insert axial lead parts, and RH machines or RHS machines are used to insert the radial lead parts. In the event that a number of components need to be installed on the printed circuit board, the number of installing paths approaches will be great. For these paths approaches, their execution efficiency is various. When a certain path approach is used for insertion, its speed may be faster than that of another path approach.
At present, the users have already adopted some approaches and numerical control programs to control the actual insertion process. However, due to the fact that in the practical manufacture, various components and points are needed, and the area of printed circuit board is great and the distribution of components is irregular (in terms of the coordinate and angles), etc, it is difficult or impossible for these man-made insertion programs to properly select an ideal paths owing to the effect of all kinds of parameters of machine, which will easily give rise to great alternation fluctuation in X and Y coordinates, feeder, insertion angle and insertion pitch in the program, and cause incessant phenomena of ‘waiting for synchronization’ in the machine. If the case is serious, it can be seen apparently that the machine will stop at times in the course of insertion, and thus leading to low insertion efficiency and a long insertion time.
For example, the inserting machines are used to insert the CRT TV printed circuit boards, with its AI production process data analysis as follows: the production data of a (404*257*1.6 mm) printed circuit board are described as follows: the number of the points of the total inserted jumper wires is 110 and the mean time of JVK machines for inserting the jumper wires is tested about 34 seconds per PCB, so it is about 0.31 seconds per point, the number of the points of the axial lead parts is 161, the number of the kinds of components is 61 and the mean time of AVK machines for inserting the axial lead parts is tested about 51 seconds per PCB, so it is about 0.317 seconds per point, the number of the points of the radial lead parts is 159 points, the number of the kinds of components is 48, and the mean time of RH machines for inserting the radial lead parts is tested about 77 seconds per PCB, so it is about 0.484 seconds per point. When comparing with the characteristic parameters of Panasert machine according to these data above-mentioned, we will find that the production process can not actually make the best use of the machines. Thereinafter we give a brief analysis of the four types of the machines.
(1) JVK machines for inserting jumper wires: the maximum theoretical speed of the machines is 0.13 seconds per element (the speed is limited on the strict conditions of the machine), without any limit on the polarity of components as long as the insertion is completed in the same direction at a time. For instance, insertion of all the elements of the angle of 0 degree (direction of X) is performed, and then insertion of all the elements of the angle of 90 degrees (direction of Y) is performed. The insertion speed is only dependent on the change in paths and insertion pitch selected by the programs. Generally, this is not taken into account by the man-made insertion programs, so a great change in the paths and the insertion pitches will slow down the insertion speed of the machines, without achieving the maximum theoretical speed basically. At present, for calculating a TV printed circuit board with 120 pieces of jumper wires in practical production, the speed shall be about 0.28 to 0.30 seconds per piece.
(2) AVK machines for inserting axial lead parts: on condition that the movement of feeder (Z axis) doesn't exceed three stations, the movement of both X and Y coordinates doesn't exceed 5 cm, the insertion pitch is unchanged and the data of the thickness of elements is unchanged, the maximum theoretical speed of the machines is 0.18 seconds per element for 0-degree angle, 0.15 seconds per element for 90-degree angle, 0.3 seconds per element for 180-degree angle and 0.27 seconds per element for 270-degree angle. However, at present it is difficult for the man-made programming methods to consider with these parameters, for actual insertion programs the coordinates X and Y, as well as Z axis for feeder, T axis for insertion pitch and large insertion angle will be subject to a great movement during insertion, which will markedly slow down the insertion speed. The actual average speed measured is 0.3 to 0.35 seconds per element.
(3) RH machines for inserting radial lead parts: it is also faced with the programming problems similar to AVK, and consideration shall be given to the movement of coordinates X and Y, and feeder (Z axis), as well as the change in height and insertion angle of component. Its maximum theoretical speed is 0.45 seconds per element. Inserting machine RHS: for insertion program, three factors as follows shall be considered, the first is movement paths of coordinates X and Y, the second is insertion angle, the third is height of component. Among them, the second and the third are the necessary parameters to the next insertion. Its maximum theoretical speed is 0.45 seconds per element.
On the whole, the existing insertion control programs can realize the task of insertion, but the existing insertion control programs only aim at the completion of insertion without considering the insertion efficiency. As a result, the insertion efficiency of existing insertion programs is very low. When the user wants to perfect the insertion efficiency, generally they will modify with the insertion control programs artificially. Such man-made modification is able to perfect some parameter data easily, but it neglects other parameter data. Therefore, the man-made modification not only needs a great deal of manpower, but also unable to improve the insertion efficiency markedly.